At the present time, because of the surge in communication and visual devices, there are many applications for image manifestation apparatus. In particular, there is a real need for image manifestation apparatus capable of producing images in a variety of colors and, in many applications, in full color.
Generally, two types of light emitting diodes are known: the edge emitting diode, which is utilized almost exclusively in conjunction with fiber optics; and surface emitting diodes.
In the prior art, the surface emitting, light emitting diodes (LED) are popular devices utilized for emitting light to produce images. Surface emitting LEDs require a very small area (5-50 .mu.ms) and are relatively easy to fabricate. Thus, surface emitting LEDs can be fabricated in large addressable arrays so that complete images can be generated by a single array.
One problem with surface emitting LEDs is the fact that they are a one predominant wavelength device. Thus, in the prior art in order to produce color images, each pixel of the image includes a plurality of LEDs, each producing a different wavelength of light. In an ideal full color device, for example, red, green and blue LEDs are grouped in each pixel, and the three LEDs have independently controlled intensities so the emitted light can be mixed and appears to produce true color. Such pixels require three times the surface area and three times the controls of a single LED.
Thus, it would be highly desirable to devise a multiwavelength LED pixel.
It is a purpose of the present invention to provide multiwavelength LED devices.
It is another purpose of the present invention to provide multiwavelength LED devices which produce a variety of wavelengths of light through a single emission aperture.
It is still another purpose of the present invention to provide methods of fabricating multiwavelength LED devices.